Generally, a gas chromatograph includes a gas injection part for injecting a sample gas, a separation column for separating the sample gas into components, a detector for detecting separated sample components, and an oven. A pipe connecting between the sample injection part and the separation column and a pipe connecting between the separation column and the detector are accommodated inside the oven together with the separation column, and temperatures thereof are adjusted. The oven is a convection oven which includes a heater and a fan, and which uniformly heats the inside of the oven by circulating the air heated by the heater inside the oven.
An example of a conventional gas chromatography device will be described with reference to FIG. 8. A sample injection part 60 and a detector 64 are attached at the upper portion of an oven 74, and, in addition to a separation column 62, a capillary 66 connecting the sample injection part 60 and the separation column 62 is accommodated inside the oven 74.
The capillary 66 includes a coil form portion 68, and the coil form portion 68 constitutes a guard column or a retention gap. The guard column is inserted between the sample injection part and the separation column with the aim of preventing pollution of the separation column by impurities or high boiling point components. Regardless of presence or absence of a liquid phase is irrelevant, the length of the path of the guard column is said to have to be about 0.5 m to 5 m. Depending on the level of pollution, the guard column may have to be replaced or partially cut. The retention gap is inserted between the sample injection part and the separation column with the aim of preventing splitting of the peak of one component or spread of peak components caused due to a high injection amount of a sample in a case where an on-column method or a splitless method is used as the sample injection method. A capillary as the retention gap has to be a deactivated capillary which is not coated with a liquid phase, and the length of the path is generally said to have to be about 0.5 m to 5 m.
Generally, in the case where a guard column or a retention gap is provided between the sample injection part and the separation column, as in FIG. 8, they are accommodated inside the oven together with the separation column, and the same temperature adjustment is performed with the separation column.
As the problems regarding the gas chromatography device described above, a slow temperature increase/decrease rate of the separation column and the great power consumption due to the size of the heat capacity of the convection oven are cited. As one method of solving the problems, temperature adjustment for the separation column by another mechanism with a smaller heat capacity than the oven is proposed, by winding of a heating wire around the separation column, for example (see Patent Document 1). According to this method, since the separation column is arranged, as a column module, outside the oven by being accommodated in a separate container in a state where a heating wire is wound around the separation column, the heat capacity of a heating target is small, and the temperature of the separation column may be increased or decreased at a high rate, and thus, responsiveness to the temperature adjustment of the separation column is improved, and power consumption at the time of increasing or decreasing the temperature of the separation column is reduced.